[en] It is essential that the acquisition of anatomical patient date is undertaken in radiotherapy treatment position. This means that the patient should be supine or prone as for treatment, the exact head pad should be used and the positioning of the limbs should be as for subsequent treatment. Any immobilisation devices such as perspex shell, vacuum bags, use of arm poles or foot boards must also be used. It is important that any internal movement such as respiration, swallowing, variability of the bladder volume size, should also be considered. The main modes of obtaining anatomical patient data are discussed i.e. use of the treatment simulator using orthogonal radiographs with rulers to provide magnification factors; computerized tomography scans and magnetic resonance imaging scans. Ideally, a combined treatment planning station is needed which can unite all forms of diagnostic imaging used in acquiring data about a patient. This is an area of ongoing research. (author). 17 refs, 4 tabs